1. Field of the Invention
This invention relates to an automatic filling capillary pipet which is adapted to receive a predetermined volume of an aqueous liquid without requiring manual effort to precisely align the liquid upper level with a pipet calibration line.
2. Description of the Prior Art
In numerous laboratory uses small diameter or micro-tubular pipets are employed in order to receive and transfer relatively small quantities of liquid. These pipets are frequently composed of tubular glass and provided with at least one volume indicating graduation in order to permit the receipt and discharge of a precisely measured volume of fluid. Liquid is frequently introduced into the pipet by suction as by a dropper type bulb or suction hose attached to the upper end thereof. Also, liquid is frequently introduced into the pipet by capillary action such as is encountered in withdrawing blood from a finger puncture in a patient.
One of the difficulties encountered in conventional pipets is the need to precisely monitor the inward flow of the fluid into the pipet. Inward flow must be terminated at the precise moment when the meniscus of the liquid in the pipet is positioned at the desired calibration line on the pipet in order to insure receipt and delivery of a specific predetermined volume of the fluid. This procedure is, of necessity, relatively slow, cumbersome and somewhat inefficient and requires a high degree of skill on the part of the user. In view of the rapid acceleration in the annual volume of clinical laboratory tests which employ pipets coupled with the need to maintain or improve the accuracy of such tests and the need to free skilled laboratory personnel for other responsibilities, there remains a substantial need for an automatic control pipet which is easy to operate, even in the hands of relatively unskilled individuals.
There remains, therefore, a need for a pipet which is adapted to automatically and rapidly transfer a precise predetermined quantity of liquid into the hollow interior without involving manual technique and human measurement coupled with all of the resultant undesirable features.